A study of physiology of the female tract was undertaken to investigate (1) the mechanism of sperm and egg transport in the female tract, (2) the development and degeneration of eggs under various conditions, (3) the effect of steroid hormones and other drugs on the transportation of gametes and implantation, especially delayed implantation, (4) the hormonal requirement for implantation and embryonic development of various species, and (5) the inhibition of implantation and interruption of pregnancy by various treatments.